Pincers for crimping sleeves on the ends of electric cables are already known from U.S. Pat. No. 2,992,576. These pincers comprise two jaws pivoted around a fixed pin and having elements adapted for said crimping at one of their ends. The other end of each jaw is connected by a pivot pin to one of the ends of a link. The two links, one for each jaw, are connected together by a pivot pin which passes through their other end and is located on the median axis of the pincers. This last-mentioned pivot pin also serves as connecting element between these two links and the upper end of a single central push member whose longitudinal axis is identical with the median axis of the pincers. The other end of said push member is connected via a pin which slides in grooves provided in the inner faces of the side plates to the center of rotation of two lever arms connected by pivot pins and via two connecting rods to the side plates of the pincers.
However, these pincers serve only for crimping a metal part and in general a part of sheet metal of slight thickness onto an electric cable and therefore the force which must be supplied is relatively slight while in order to cut a bolt and/or a round rod the force which must be supplied is very substantial. Thus in order to actuate the pincers of said U.S. patent, the free ends of the lever arms are brought together and a push is exerted on the central push member. Under the action of this central push member, the two links move out laterally which results in a lateral push being exerted on the ends of the jaws causing them to rotate and therefore to bring together the two elements contemplated for the crimping.
There are also known, from U.S. Pat. No. 2,229,263, pincers which serve in most cases either as flat-nosed pliers or as nippers. These pincers comprise two lever arms provided at their front end with two holes through which pivot pins are engaged. One of these pivot pins serves, on the one hand, as connecting element between the lever arm and one of the jaws and, on the other hand, as axis of rotation for said jaw while the other pivot pin serves as connecting element between said same lever arm and the other jaw. In this way, each jaw has two holes arranged on opposite sides of an opening.
However, there are concerned here simple pincers which, serving as nippers, permit the cutting only of metallic parts of small diameter since the unit is by no means designed to cut bolts or iron bars. Furthermore, the principle of these pincers is entirely different from a bolt cutter, such as forms the object of the present invention since during operation there is displacement in one direction of the connecting pins and displacement in the other direction of the rotation pins of the jaws.
Similarly from French Pat. No. 74.06037 there is known a bolt cutter which comprises two blades pivoted on a common support, two arms also pivoted on this same support, and means for transmitting forces and movements between the blades and the arms. The blades and the arms are pivoted on pins which are fixed in position in the common support which is formed by at least one cheek while the front ends of the arm are arranged between the rear ends of the blades and the means for transmitting the forces between each arm and blade are formed of a link whose ends are pivoted, one to the rear end of the blade and the other to the front end of the corresponding arm. Each link has at its two ends a cylindrical enlargement adapted to be fitted in a semi-cylindrical recess provided in the rear portion of each blade and in the front portion of each arm respectively. Each arm has at its front end opposite its homolog, on the one hand a stop face arranged behind its pivot pin on the cheeks and intended to cooperate with the corresponding face of the facing arm in order to limit the angle of closure of the two arms to a value which is compatible with human morphology and on the other hand a stop face arranged in front of the said pivot pin and intended to limit the maximum angle of opening so that the maximum value of the distance between two handles fastened to the rear ends of the arms is not greater than human possibilities.
In this cutting device, the force is a push force. When it is desired to move the two articulated blades apart, the semi-cylindrical recess of the front portion of each arm exerts a pull on the cylindrical enlargement of the link. The latter, by its second enlargement, exerts a pull on the semi-cylindrical recess of the rear portion of each blade. However, the forces exerted on the semi-cylindrical recesses of the arm and/or of the blade are concentrated on the portions of these recesses which are located beyond the diameter of the said recesses. Therefore, there is obtained premature wear or even a breaking of these parts, resulting in a disconnection between the links and the arms and/or articulated blades. Moreover, these recesses have an open region and therefore the risk of the penetration of foreign bodies.